Structures of new acidic O-specific polysaccharides of the bacterium Proteus mirabilis serogroups O26 and O30

AbstractThe polysaccharide chains of the lipopolysaccharides of the Proteus mirabilis serogroups O26 and O30 were studied using sugar and methylation analysis and 1H and 13C NMR spectroscopy, including two-dimensional correlation spectroscopy and rotating-frame NOE spectroscopy. The polysaccharides were found to be acidic due to the presence of d-galacturonic acid and its amide with l-lysine in serogroup O26 or d-glucuronic acid in serogroup O30, and the structures of their tetrasaccharide repeating units were established. The O26-specific polysaccharide is structurally and serologically related to the O-specific polysaccharide of P. mirabilis O28, which includes amides of d-GalA with l-lysine and l-serine [Radziejewska-Lebrecht, J. et al. (1995) Eur. J. Biochem. 230, 705–712]

A novel plasmid-encoded serotype conversion mechanism through addition of phosphoethanolamine to the O-antigen of Shigella flexneri

Abstract Shigella flexneri is the major pathogen causing bacillary dysentery in developing countries. S. flexneri is divided into at least 16 serotypes based on the combination of antigenic determinants present in the O-antigen. All the serotypes (except for serotype 6) share a basic O-unit containing one N-acetyl-D-glucosamine and three L-rhamnose residues, whereas differences between the serotypes are conferred by phage-encoded glucosylation and/or O-acetylation. Serotype Xv is a newly emerged and the most prevalent serotype in China, which can agglutinate with both MASF IV-1 and 7,8 monoclonal antibodies. The factor responsible for the presence of MASF IV-1 (E1037) epitope has not yet been identified. In this study, we analyzed the LPS structure of serotype Xv strains and found that the MASF IV-1 positive phenotype depends on an Oantigen modification with a phosphoethanolamine (PEtN) group attached at position 3 of one of the rhamnose residues. A plasmid carried gene, lpt-O (LPS phosphoethanolamine transferase for O-antigen), mediates the addition of PEtN for serotype Xv and other MASF IV-1 positive strains. These findings reveal a novel serotype conversion mechanism in S. flexneri and show the necessity of further extension of the serotype classification scheme recognizing the MASF IV-1 positive strains as distinctive subtypes

K19 capsular polysaccharide of acinetobacter baumannii is produced via a Wzy polymerase encoded in a small genomic island rather than the KL19 capsule gene cluster

© 2016 The Authors.Polymerization of the oligosaccharides (K units) of complex capsular polysaccharides (CPSs) requires a Wzy polymerase, which is usually encoded in the gene cluster that directs K unit synthesis. Here, a gene cluster at the Acinetobacter K locus (KL) that lacks a wzy gene, KL19, was found in Acinetobacter baumannii ST111 isolates 28 and RBH2 recovered from hospitals in the Russian Federation and Australia, respectively. However, these isolates produced long-chain capsule, and a wzy gene was found in a 6.1 kb genomic island (GI) located adjacent to the cpn60 gene. The GI also includes an acetyltransferase gene, atr25, which is interrupted by an insertion sequence (IS) in RBH2. The capsule structure from both strains was→3)-α-D-GalpNAc-(1→4)-α-D-GalpNAcA-(1→3)-β-D-QuipNAc4NAc-(1→, determined using NMR spectroscopy. Biosynthesis of the K unit was inferred to be initiated with QuiNAc4NAc, and hence the Wzy forms the β-(1→3) linkage between QuipNAc4NAc and GalpNAc. The GalpNAc residue is 6-O-acetylated in isolate 28 only, showing that atr25 is responsible for this acetylation. The same GI with or without an IS in atr25 was found in draft genomes of other KL19 isolates, as well as ones carrying a closely related CPS gene cluster, KL39, which differs from KL19 only in a gene for an acyltransferase in the QuiNAc4NR synthesis pathway. Isolates carrying a KL1 variant with the wzy and atr genes each interrupted by an ISAba125 also have this GI. To our knowledge, this study is the first report of genes involved in capsule biosynthesis normally found at the KL located elsewhere in A. baumannii genomes

Metallothionein I as a direct link between therapeutic hematopoietic stem/progenitor cells and cerebral protection in stroke

National Institutes of Health/National Heart, Lung, and blood Institute (NIH/NHLBI (HL125572-01A1)); Malcolm Feist Cardiovascular Fellowship program; National Institute of General Medical Sciences COBRE Grant (P30- GM110703) and Japan Society for the Promotion of Science (Grants-in-Aid for Scientific Research- KAKENHI, 16H07356)

Structure of the capsular polysaccharide of Acinetobacter baumannii 1053 having the KL91 capsule biosynthesis gene locus

© 2014 Elsevier Ltd. All rights reserved. Acinetobacter baumannii 1053 is the type strain for the maintenance of specific bacteriophage AP22, which infects a fairly broad range of A. baumannii strains circulating in Russian clinics and hospitals. A capsular polysaccharide (CPS) was isolated from cells of strain 1053 and studied by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy. The following structure of the linear trisaccharide repeating unit was established: →4)-β-D-ManpNAcA-(1→4)-β-D-ManpNAcA-(1→3)-α-D-FucpNAc-(1→ where ManNAcA and FucNAc indicate 2-acetamido-2-deoxymannuronic acid and 2-acetamido-2,6-dideoxygalactose, respectively. A polysaccharide having the same repeating unit but a shorter chain was isolated by the phenol-water extraction of bacterial cells. Sequencing of the CPS biosynthesis gene locus showed that A. baumannii 1053 belongs to a new group designated KL91. The gene functions assigned putatively by a comparison with available databases were in agreement with the CPS structure established

Targeting of Formyl Peptide Receptor 2 for in vivo imaging of acute vascular inflammation

© The author(s). Inflammatory conditions are associated with a variety of diseases and can significantly contribute to their pathophysiology. Neutrophils are recognised as key players in driving vascular inflammation and promoting inflammation resolution. As a result, neutrophils, and specifically their surface formyl peptide receptors (FPRs), are attractive targets for non-invasive visualization of inflammatory disease states and studying mechanistic details of the process. Methods: A small-molecule Formyl Peptide Receptor 2 (FPR2/ALX)-targeted compound was combined with two rhodamine-derived fluorescent tags to form firstly, a targeted probe (Rho-pip-C1) and secondly a targeted, pH-responsive probe (Rho-NH-C1) for in vivo applications. We tested internalization, toxicity and functional interactions with neutrophils in vitro for both compounds, as well as the fluorescence switching response of Rho-NH-C1 to neutrophil activation. Finally, in vivo imaging (fluorescent intravital microscopy [IVM]) and therapeutic efficacy studies were performed in an inflammatory mouse model. Results: In vitro studies showed that the compounds bound to human neutrophils via FPR2/ALX without causing internalisation at relevant concentrations. Additionally, the compounds did not cause toxicity or affect neutrophil functional responses (e.g. chemotaxis or transmigration). In vivo studies using IVM showed Rho-pip-C1 bound to activated neutrophils in a model of vascular inflammation. The pH-sensitive (“switchable”) version termed Rho-NH-C1 validated these findings, showing fluorescent activity only in inflammatory conditions. Conclusions: These results indicate a viable design of fluorescent probes that have the ability to detect inflammatory events by targeting activated neutrophils.British Pharmacological Society; Wilkinson Trust; EPSRC; German Research Foundation

The o-specific polysaccharide chain of campylobacter fetus serotype b lipopolysaccharide is a d-rhamnan terminated with 3-o -methyl-d-rhamnose (d-acofriose)

An O-specific polysaccharide was liberated from Campylobacter fetus subsp. fetus serotype B lipopolysaccharide by mild acid hydrolysis followed by gel chromatography. This polysaccharide was found to contain D-rhamnose and 3-O-methyl-D-rhamnose (D-Rha3Me, D-acofriose) in a ratio of approximately 24:1, as well as lipopolysaccharide core constituents. The structure of the polysaccharide was studied by H-1-NMR and C-13-NMR spectroscopy, which included two-dimensional COSY, rotating-frame NOE spectroscopy (ROESY), and computer-assisted analysis of the C-13-NMR spectrum. Methylation analysis using [H-2(3)]methyl iodide and Smith degradation followed by GLC/MS of the derived acetylated oligosaccharide-alditols was used to determine the location of D-acofriose. The O-specific polysaccharide is linear, consists on average of 12 disaccharide repeating units, and is terminated by a residue of D-acofriose. The following structure of the D-rhamnan chain was established: [GRAPHICS] and fumarate as oxidant. Steady-state kinetics for the oxidase and the fumarate reductase activity of L-aspartate oxidase were obtained using either fumarate or oxygen as electron acceptor and L-aspartate as electron donor. Finally, succinate was identified as the product of the L-aspartate:fumarate oxidoreductase activity using radiolabeled fumarate under anaerobic conditions. The results suggest that fumarate can be a valuable alternative to oxygen as a substrate for L-aspartate oxidase